I inadvertently connected a serial port on an older Dell D300 to the s-video on a newer (to me) Inspiron 5160. Now my usb ports are not working. I ran every diagnostic I could find, and everything says it is operating perfectly. I tried 4 different devices, and the computer does not recognize anything plugged into the usb. Any ideas? Did I fry something expensive? Thanks.

Hmm, serial port and s-video are two TOTALLY different connectors, how did you manage to do that? Are you positive its s-video?

Serial ports carry dc voltages on several of the pins (around +/- 8-15V). So depending on which pins were mated to which pins, the TV encoder chip may be damaged. Plug a s-video cable from your Inspiron to your TV, its it working?

When you plug in a usb device, do any led's light up? For example, a usb flash key?

This determines that the usb is providing the required power, should be +5V.

There shouldn't be anything connecting s-video and usb. Try the above tests and let us know.:)

HVAC888... I'll bet there's a story there.

Don't even ask about the cable. I have no idea where it came from or why it exists. I was just messing with it trying to find out whether it was an s-video or a mouse plug. Unfortunately, the other end was plugged into my old desktop.

It's s-video. I tried hooking it to the input on my TV, but no signal. Function F8 made it blip, but that's it. I'm assuming the other end is a 9-pin serial port. Obviously, I'm no guru, just dangerous.

Oddly, usb devices do not light up, but if I plug in, remove, and plug in again, one of my thumb drives does light up. All the other devices do nothing. The computer does not recognize anything in the usb ports.

I uninstalled root hubs and controllers and updated them to no avail. No nasty comments in the device manager. It thinks everything's rosy.

Thanks again for your help. Any other ideas? I'm not afraid to rip into this thing. Maybe I should be.

You could try a powered usb hub. This way the usb device is powered by an external source.